*::after, *::before {
  box-sizing: border-box;
}

*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  scroll-behavior: smooth;
}

:root {
  --clr: #2c363f;
}

body {
  background: var(--clr);
}

header {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: #2196f3;
  padding: 10px 50px;
  display: flex;
  justify-content: flex-start;
  align-items: center;
  z-index: 10000;
  gap: 60px;
}

header .logo {
  position: relative;
  color: #fff;
  font-size: 2em;
  font-weight: 600;
  text-decoration: none;
}

header nav {
  display: flex;
  gap: 10px;
}

header nav a {
  position: relative;
  text-decoration:  none;
  padding: 12px 20px;
  color: #fff;
  letter-spacing: .1em;
  font-weight: 400;
}

header nav #indicator {
  position: absolute;
  width: 85px;
  height: 58px;
  background: var(--clr);
  border-top-left-radius: 20px;
  border-top-right-radius: 20px;
  transition: .5s;
}

header nav #indicator::before {
  content: '';
  position: absolute;
  bottom: 0;
  left: -30px;
  width: 30px;
  height: 30px;
  background: transparent;
  border-bottom-right-radius: 20px;
  box-shadow: 5px 5px 0 5px var(--clr);
}

header nav #indicator::after {
  content: '';
  position: absolute;
  bottom: 0;
  right: -30px;
  width: 30px;
  height: 30px;
  background: transparent;
  border-bottom-left-radius: 20px;
  box-shadow: -5px 5px 0 5px var(--clr);
}